The subject matter disclosed herein relates to a variable area fuel nozzle.
Dry Low NOx (DLN) combustors are widely used for power generation as well as oil and gas production applications and are mainly designed for use with natural gas fuel and/or liquid fuels. New applications of the combustors are, however, beginning to demand that the combustors exhibit wider fuel flexibility. For example, in many cases currently operating combustors must have the capability to operate on natural gas fuels and then switch to low British Thermal Unit (BTU) fuels where fuel flow rates double and still meet emissions and operability requirements.
In these cases, as fuel flow rates of the alternate fuels can be significantly greater than those of other fuels, additional circuits need to be installed to maintain fuel side pressure ratios to satisfy fuel delivery specifications. These additional circuits often require active controls, purge circuits and/or additional equipment and are, therefore, expensive and costly to maintain. In addition, dynamics effects due to varying pressure levels within the circuits can be problematic.